How to classify gear oil grades
Gear oil is an indispensable lubricant in mechanical equipment, especially in gear transmission systems. The grade classification of gear oil is directly related to its performance and application scenarios. This article will introduce in detail the classification standards and classification methods of gear oil and how to choose the appropriate gear oil.
1. Gear oil grade classification standards
The classification of gear oils is mainly based on their viscosity grade and performance grade. Viscosity grades usually use SAE (Society of Automotive Engineers) standards, while performance grades refer to API (American Petroleum Institute) or ISO (International Organization for Standardization) standards.
| Standard | Classification basis | Common levels |
|---|---|---|
| SAE | viscosity | 75W, 80W, 85W, 90, 140, 250 |
| API | Performance | GL-1, GL-2, GL-3, GL-4, GL-5 |
| ISO | viscosity | VG 68, VG 100, VG 150, VG 220, VG 320 |
2. SAE viscosity grade classification
SAE viscosity grade is one of the most common classification methods of gear oil, which is mainly divided into single-grade oil and multi-grade oil. Single-grade oil is suitable for environments with small temperature changes, while multi-grade oil is suitable for environments with large temperature changes.
| SAE grade | Applicable temperature range | Typical applications |
|---|---|---|
| 75W | -40°C to 10°C | Extremely cold areas |
| 80W | -26°C to 20°C | cold areas |
| 85W | -12°C to 30°C | temperate zone |
| 90 | -10°C to 35°C | Ordinary area |
| 140 | 10°C to 50°C | high temperature area |
| 250 | 20°C to 60°C | Extremely high temperature areas |
3. API performance level classification
API performance levels are divided based on the extreme pressure performance, oxidation resistance and corrosion resistance of gear oils. Different performance levels are suitable for different gear types and operating conditions.
| API level | Applicable gear type | Main features |
|---|---|---|
| GL-1 | Low load spiral bevel gear | Does not contain extreme pressure additives |
| GL-2 | Worm gear | Contains small amounts of extreme pressure additives |
| GL-3 | Medium load spiral bevel gear | Moderate extreme pressure performance |
| GL-4 | High load spiral bevel gear | High extreme pressure performance |
| GL-5 | High load hypoid gear | Extremely high extreme pressure performance |
4. ISO viscosity grade classification
The ISO viscosity grade is mainly used to classify industrial gear oils. Its numerical value indicates the kinematic viscosity of the gear oil at 40°C (unit is cSt).
| ISO grade | Kinematic viscosity (40°C, cSt) | Typical applications |
|---|---|---|
| VG 68 | 61.2-74.8 | light duty gears |
| VG 100 | 90-110 | Medium load gear |
| VG 150 | 135-165 | Heavy Duty Gears |
| VG 220 | 198-242 | Extremely heavy duty gears |
| VG 320 | 288-352 | Extra heavy duty gears |
5. How to choose the appropriate gear oil
When choosing the right gear oil, you need to consider the following factors:
1.working temperature:Select the corresponding SAE viscosity grade according to the working environment temperature of the equipment.
2.Gear type: Different types of gears (such as spiral bevel gears, hyperbola gears, etc.) have different performance requirements for gear oil. Please refer to the API grade.
3.load conditions: High-load gears need to choose gear oil with better extreme pressure performance (such as GL-4 or GL-5).
4.Equipment manufacturer recommendations: Follow the equipment manufacturer's recommendations to ensure the gear oil is compatible with the equipment.
6. Summary
The classification of gear oil is a key factor in ensuring the normal operation of equipment. By understanding standards such as SAE, API and ISO, users can more accurately select suitable gear oils. Whether it is viscosity grade or performance grade, it should be selected according to actual working conditions and equipment requirements to ensure efficient lubrication and long-term stable operation of the gear system.
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